The process of obtaining a biological or other fluid sample such as blood and the subsequent centrifugation process generally requires multiple steps and devices, including the transferring of the sample from the syringe used to obtain the sample to a separate centrifugation syringe. These steps increase the overall inconvenience, costs, and time necessary to perform the procedure by requiring handling by medical personnel and the sterilization and use of multiple devices. In addition, risks of contamination of the sample and/or infection of the medical personnel are increased as the amount of handling and the number of devices used are increased.
The application of the separation and mixing system described below uses, merely as an example, blood as the fluid sample. After a centrifugation process of blood, separated plasma may be mixed with a coagulation solution from another syringe into a mixer. The resulting multi-component mixture can be used as a mixed tissue adhesive for seamlessly or seam-supportingly connecting human or animal tissue or organ parts, for sealing wounds, stopping bleeding and the like. For applications such as sealing cerebrospinal fluid leakage, a very high degree of homogeneity of the multi-component mixture is desirable and often necessary due to high pressure transients. Thorough mixing of sealant components is desirable to maximize strength of the polymerized sealant. However, prior art mixers generally do not achieve a sufficient level of mixing in a fast enough time, especially where the viscosity ratio between the two components is relatively high.
A common prior art mixer is a helical mixer whose primary type of flow is a shear flow. An example of a similar method for mixing multi-part compositions is disclosed in U.S. Pat. No. 5,328,462 to Fischer, which utilizes the rotation of a mixer element within a syringe barrel to mix components.
After mixing the components, the mixture is then discharged from the mixer. Most prior art and commercial pressure nozzles are of the swirl-type that must first produce a centrifugal velocity on the mixture immediately prior to its being discharged from the exit orifice. The prior art helical mixer accomplishes this by forcing the mixture into a swirl chamber, sending the mixture through spiral channels, and imparting a circular motion superimposed onto the axial velocity of the mixture. Thus, a helical mixer or a separate swirling mechanism must be used to effect the swirl-type method of discharging the mixture.